Jamo R909 Floor standing speakers

Acoustics, created lately by the company "Jamo", cannot be considered as usual. Each model has its own twist: heather location of speakers, extravagant appearance, unique characteristics... But even in the light of this tendency it is hard to stay calm looking at the flagship floor pair: they are not trivial cabinet loudspeakers, but the rarest open speaker systems. They are the rarest, because nobody creates speaker systems of "acoustical baffle" type, thinking that the game is not worth the candle. The matter is that it is impossible to get a significant increase, provided by the screen, in the sound quality without preparatory solving of very many problems. The first and foremost problem is acoustic "short circuit" at low frequencies that is inevitable for such construction. In order to the radiation of the front side of speaker wasn't compensated by anti-phase back radiation, you need such a screen, the radius of which will be bigger than wave length. Let's estimate: 100 Hz- this is 3 with a half meters! I think the comments are unnecessary because the wave length increases with decrease of frequency.

You can get rid of "short circuit" only bluntly: greatly increasing the area of the emitter and developing its own sensitivity to cosmic values. No sooner said than done. Two giant (380 mm) "hats" with ultra-light diffusers made of uncompacted paper, greatly resisting bending oscillations. It is clear that the construction of these speakers fundamentally differs from traditional heads, designed for phase-inverted or closed arrangement of speaker systems: their own resonant frequency is much lower and in addition they have extremely low quality. In the result the sensitivity of each LF-speaker exceeds 100 dB - it is the level of professional stage heads. Jamo ordered the speakers for MF and HF sections from neighbors - "Seas" Norwegian company and the Danish "Scan Speak". Mid-frequency emitter of Seas is equipped with very light and rigid diffuser made of magnetic alloy and also having a high efficiency, patented by neodymium magnetic system. In addition a silver "bullet" of dust-proof cap looks quite harmoniously. The tweeter here is not just simple but which gained a legendary status of Scan Speak Revelator. Its fabric dome is covered with a special compound, which increases the stiffness without compromising weight. Actually the HF-speaker is slightly modified in comparison with the factory Revelator - if the original version was framed with a fairly wide horn, here we see absolutely flat podium of modest diameter. Few words about the screen.

This is a massive slab with thickness of 43 mm, glued of 7 MDF layers and curved under high pressure. Its rigidity is titanic! And although vibration resistance of carcass at such acoustic design doesn't play a special role, we should notice the accuracy of the developers' approach. Apparently in order to emphasize the technological intension of its speaker systems the developer chose bright coloring: there are black piano, rich red and sunny yellow. Finishing touch is puff (metal-MDF-metal) keel as if coming out of the tweeter and resting, just as the screen itself, on the pedestal.

The main advantage of acoustic screen (in addition to compactness, which can't be seriously considered as plus in such speaker systems) is a correct playing of the low-frequency range. The roll-off of AFC happens more smoothly than even in closed cabinet speaker system: approximately 6 dB peer octave if to believe the factory measurements. The same is relative to group time delay - it's less than in closed loudspeakers not mentioning the phase-inverted. In practice this is expressed in tonal accuracy and excellent legibility of bass passages. The double-bass in "Piece by Piece" of Katie Melua, sounding usually boomy in phase-inverted acoustics, is played here tight, scaly and with incredibly acute attack. No wonder that this type of speakers in English is called Velocity Transducer, that means "the converter of speed". In this design the masking effect, which LF-section has in any phase-inverted speaker systems, reduces very much and this helps to combine another heads with the firmed Jumo woofers in the gentlest way. We can talk about filigree dock of emitters. The nuances of vocal range and the texture of percussive instruments are transmitted excellently - the speakers are matched without a doubt perfectly! Open speaker systems have truly one feature, which can be seemed to be fatal: in no case they can't be put up to wall, although the form hints at this. Nothing good will happen, if the reflected component (acoustics also emits to the back, in antiphase) is not sufficiently weakened. In addition, the speaker systems need space for correct work -there is no sense to put such pair into the room of 20 m2. Ideally Jamo R909 should be placed in acoustically prepared room of 40 m2 and bigger, but the acoustic processing, not room, still has the main meaning.